In order to investigate the crossing behavior of inclusion at slag/droplet interface during ESR process, a 2D mathematical model was developed and solved by Matlab. Results showed that the inclusion transport across the slag/droplet interface can be divided into three types: pass, oscillation and rebound. Further discussion about influencial factors indicated that inclusions with higher initial velocity were easier to pass through the interface, and the increase of initial velocity angle and interface angle would hinder the cross behavior. Moreover, research also showed that at lower initial velocity of inclusions, this cross behavior was dominated by interface angle but the influence degree of initial velocity angle gradually grew with the initial velocity increasing.